This invention relates to an information processing system for use in combination with a duplex storage comprising first and second storages for storing same data.
In an information processing system of the type described, each of the first and the may be a magnetic disk storage, a magnetic tape storage or the like.
As will later be described in detail, a conventional information processing system comprises a bus and a main memory comprising a data area connected to the bus. The conventional information processing system further comprises a central processor connected to the bus, a first storage controller connected to the bus and to the first storage, and a second storage controller connected to the bus and to the second storage. When the central processor makes the first and the second storage controllers carry out data transfer from the data area of the main memory to the first and the second storages, the central processor produces, on the bus, a first write control signal indicative of data transfer from the main memory to the first storage at first. In response to the first write control signal received from the bus, the first storage controller carries out the data transfer from the data area of the main memory to the first storage through the bus. Thereafter, the central processor produces, on the bus, a second write control signal indicative of data transfer from the main memory to the second storage. In response to the second write control signal received from the bus, the second storage controller carries out the data transfer from the data area of the main memory to the second storage through the bus.
With this structure, the central processor is subjected to increased overhead, because the central processor produces the first and the second write control signals individually for the first and the second storage controllers. In addition, the bus is subjected to increased overhead. This is because the bus is used not only when the data transfer is carried out from the data area of the main memory to the first storage but also when the data transfer is carried out from the data area of the main memory to the second storage. Thus, the conventional information system is incapable of efficiently carrying out data transfer from the main memory to the duplex storage.